The present invention relates to a new and distinct, nearly seedless variety of hybrid mandarin (tangerine) for the fresh citrus market named ‘N40W-6-3’. ‘N40W-6-3’ was selected from a population of 50 plants grown from irradiated budwood (cobalt 60, Vindicator Co., Mulberry, Fla.) from ‘Snack’ (unpatented), a seedy mandarin hybrid of unknown parentage. Irradiation treatment of budwood is known to induce mutations that, in rare instances, cause a permanent genetic change in a variety to greatly reduce or eliminate seed in fruit, without otherwise altering the integrity of the variety. ‘N40W-6-3’ was first asexually propagated by grafting to experimental rootstock Orange #14 (unpatented) and planted in Lake Alfred, Fla., in 2011. Asexually propagated trees of ‘N40W-6-3’ have remained true-to-type to the original selection through successive generations.